x86/dumpstack: Unify show_regs()

The 32-bit version uses KERN_EMERG and commit

  b0f4c4b32c8e ("bugs, x86: Fix printk levels for panic, softlockups and stack dumps")

changed the 64-bit version to KERN_DEFAULT. The same justification in
that commit that those messages do not belong in the terminal, holds
true for 32-bit also, so make it so.

Make code_bytes static, while at it.

Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Link: https://lkml.kernel.org/r/20180306094920.16917-4-bp@alien8.de

1 files changed, 48 insertions, 1 deletions

diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index a2d8a3908670..18fa9d74c182 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -24,7 +24,7 @@
 
 int panic_on_unrecovered_nmi;
 int panic_on_io_nmi;
-unsigned int code_bytes = 64;
+static unsigned int code_bytes = 64;
 static int die_counter;
 
 bool in_task_stack(unsigned long *stack, struct task_struct *task,
@@ -375,3 +375,50 @@ static int __init code_bytes_setup(char *s)
 	return 1;
 }
 __setup("code_bytes=", code_bytes_setup);
+
+void show_regs(struct pt_regs *regs)
+{
+	bool all = true;
+	int i;
+
+	show_regs_print_info(KERN_DEFAULT);
+
+	if (IS_ENABLED(CONFIG_X86_32))
+		all = !user_mode(regs);
+
+	__show_regs(regs, all);
+
+	/*
+	 * When in-kernel, we also print out the stack and code at the
+	 * time of the fault..
+	 */
+	if (!user_mode(regs)) {
+		unsigned int code_prologue = code_bytes * 43 / 64;
+		unsigned int code_len = code_bytes;
+		unsigned char c;
+		u8 *ip;
+
+		show_trace_log_lvl(current, regs, NULL, KERN_DEFAULT);
+
+		printk(KERN_DEFAULT "Code: ");
+
+		ip = (u8 *)regs->ip - code_prologue;
+		if (ip < (u8 *)PAGE_OFFSET || probe_kernel_address(ip, c)) {
+			/* try starting at IP */
+			ip = (u8 *)regs->ip;
+			code_len = code_len - code_prologue + 1;
+		}
+		for (i = 0; i < code_len; i++, ip++) {
+			if (ip < (u8 *)PAGE_OFFSET ||
+					probe_kernel_address(ip, c)) {
+				pr_cont(" Bad RIP value.");
+				break;
+			}
+			if (ip == (u8 *)regs->ip)
+				pr_cont("<%02x> ", c);
+			else
+				pr_cont("%02x ", c);
+		}
+	}
+	pr_cont("\n");
+}